Parachute recovery system for fuze testing



May 26, 1970 T. l. HANNOLD 3,513,777

PARACHUTE RECOVERY SYSTEM FOR FUZE TESTING Filed March 5. 1968 United. States Patent O f UNS. Cl. 1024-56 5 Claims ABSTRACT F THE DISCLOSURE A testing and recovery system to test an unmodified fuze` with a standard projectile and to recover the fuze after operation but before destruction of the projectile by impact with the ground. The system additionally gives an indication of the point on the projectile trajectory at which the fuze operated.

The invention described herein may be manufactured, used and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION During the testing phasesof the development programs for proximity and other nose mounted type fuzes, it is desirable to have a means of recovering the fuzes after operation but before they are destroyed or damaged by impact with the ground. Recovery would allow the examination of the fuze to determine the cause of malfunction` where one occurs. Even where the fuze operated according to its design specification it is still important to examine the fuze before impact so that the structure and partsz can be analyzed to determine the performance of the `fuze components. Related to the problem of fuze recovery is the problem `of determining the point on the trajectory where the fuze operated. A determination of the `operation point will indicate whether the fuze operated as designed or whether it malfunctioned by operating before or after its designed operating point.

Previous systems have utilized parachute recovery systems that were initiated by an independent timer mechanism in the projectile which operated at any point in the trajectory after fuze operation. Where the timer malfunctioned the fuze was destroyed. Such systems have the added disadvantage of not allowing identification of the point on the trajectory at which the fuze operated. Other systems have triggered a parachute recovery system after extensive modification of the fuze so that the parachute would deploy upon operation of the fuze. This type of system defeats the primary purpose of the testing program, that being to test the unmodified fuze.

It is therefore an object of the present invention to provide a means of testing and recovering a proximity or nose type fuze.

An additional object of the invention is to provide a fuze testing and recovery system for proximity or nose type fuzes which will allow recovery of the fuze after operation but before destruction by impact with the ground.

Still another object of the invention is to provide a fuze testing and recovery system for proximity or nose type fuzes `which will provide an indication of the point on the trajectory at which the fuze operated.

Still yet another object of the invention is to provide a fuze testing and recovery system for proximity and nose typefuzes which does not necessitate any modification of the tested fuze.

3,5 13 ,7 77 Patented May 26, 1970 ice SUMMARY OF THE INVENTION An unmodified fuze is screwed into a fuze holder which is a cylindrical body having a parachute tted around its exterior and designed to fit into a cavity in a modified projectile body. When the fuze is set into operation at some point in the projectile trajectory, it will initiate an explosive relay train which will fire an expelling charge within the projectile body. The resulting pressure buildup will force the fuze holder and parachute out of the projectile-body, allowing the parachute ton open in the air stream. The parachute will then lower the fuze to the ground for subsequent examination and inspection.

BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the invention, as Well as other objects, aspects, uses and advantages thereof, will clearly appear from the following description and from the accompanying drawing, in which:

FIG. 1 is an axial view of an embodiment of a fuze testing and recovery system in accordance with the present invention.

FIG. 2 is a sectional view of a modified projectile body for a fuze testing and recovery system in accordance With my invention.

FIG. 3 is a sectional view of a fuze holder of the fuze testing and recovery system in accordance with my invention.

FIG. 4 is a sectional view of an explosive relay train used in the fuze testing and recovery system in accordance with my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows the fuze testing and recovery system in assembled form. The system is adapted to lbe inserted into the front of a standard propelling charge by means of a threaded engaging means 14.

The modified projectile body 10 is shown in FIG. 2 and has a fuze holder well 12 into which the fuze and parachute recovery system of the invention is inserted. The fuze holder well 12 is designed to accept the fuze holder 20 shown in FIG. 3. The fuze holder 20 is a cylindrical structure and has a cavity 23 into which a standard unmodified fuze can be screwed so as to engage i11- ternal threads 30. The holder 20 has holes 26 and 28 in its walls to accept shear pins which lock the holder assembly 20 into the body assembly. Relay holder well 40 has a thread 3'6 at one end to allow for the fastening of an explosive relay train into the holder well 40. The parachute is packed in regions 42 and 44 around the fuze holder 20. Groove 50 is adapted to have an O-ring inserted therein so as to maintain a lirm pressure contact with the inner wall of the fuze holder well 12 of the projectile body 10.

The explosive relay holder 64 is shown in FIG. 4. The relay holder 64 has an explosive charge 60 which ignites a mild detonating cord 66 which in turn will ignite expelling charge 68 at the opposite end of the relay holder. The holder has a thread 62 which is adapted to engage thread 36in the fuze holder 20.

Referring again to FIG. l, it is seen that the body 10 has the fuze holder 20 inserted into its open end. The fuze holder 20 will not completely iill the fuze holder well 12 but will leave an ignition chamber 80. After the fuze holder 20 is inserted into the projectile body 10, shear pins 70 are inserted through the wall of body 10 so as to engage the holes provided in the fuze holder 20. The shear pins insure that the fuze holder will remain in place within the projectile body until a suflicient force is developed within the adapter to shear the pins. During assembly, an O-ring 74 is inserted into the groove 50 provided in the 3 fuze holder 20 to insure that there is a rm pressure contact between the fuze holder 20 and the body 10 so that any pressure in the ignition chamber 80 will not escape.

In order to test a fuze the system is attached by engaging means 14 to the front of a standard projectile. When the projectile is fired, the fuze will operate at some point on the trajectory and will initiate operation of the explosive relay train 64. This in turn will cause combustion of the expelling charge 68 and cause a pressure to buildup within the ignition chamber `80. This pressure will be applied against the end 52 of the relay fuze holder 20 and will shear pins 70 forcing the fuze holder 20 out of the front end of the projectile body 10. Once caught in the wind stream, the parachute will deploy and lower the fuze holder.20 with the fuze screwed therein tothe ground. The projectile body will continue on its trajectory and eventually be destroyed on impact.

By using a fuze testing and recovery system in accordance with my invention it becomes possible to recover the fuze without its destruction. Additionally, the point on the trajectory at which the parachute deploys will indicate the point of operation of the fuze. If parachute deployment indicates that the fuze operated prematurely, the fuze can then be recovered and thoroughly examined to determine the exact cause of the malfunction.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

I claim as my invention:

1. A fuze testing and recovery system comprising:

(a) a projectile body having a well therein,

(b) a fuze holder mounted in said well,

(c) an ignition chamber in said projectile body,

(d) an expelling charge located adjacent said ignition chamber,

(e) a fuze cavity contained within said fuze holder and adapted to receive an unmodified fuze,

(f) an explosive charge located adjacent said fuze cavity and capable of being ignited by said unmodified fuze,

(g) means connecting said explosive charge with said expelling charge, said means comprising a mild detonating cord capable of being ignited by said explosive charge, and

(h) a parachute attached to said fuze holder and disposed around the exterior surface of said fuze holder.

2. A fuze testing and recovery system of claim 1 wherein an O-ring is placed around the end of the fuze holder nearest the ignition chamber so that it maintains contact with the inner wall of the projectile body and prevents the pressure from escaping the ignition cavity before it can buildup sufficient force to cause the fuze holder to separate from the projectile body.

3. A fuze testing and recovery system of claim 2 wherein the fuze holder is held in position within the projectileY body by shear pins placed so as to pass through holes in the fuze holder and projectile body walls.

4. The system of claim 1 wherein the length of said fuze holder is less than the length of said well, and said ignition chamber is defined by that portion of the well which is not occupied by said fuze holder.

S. A fuze testing and recovery system of claim 1 Wherein the projectile body is designed to be attached to a propelling means.

References Cited UNITED STATES PATENTS 2,402,716I 6/1946y Whitsett 102-56 2,690,126 9/ 1954 Finken et al. 102-56 3,094,934 6/1963 Anthony 10Q-56 3,129,663 4/ 1964 Schnepfe 1021-70 X 3,320,884 5/1967 Kowalick et al. 102-70 X 1,947,834 2/1934 Driggs et al IGZ-35.6 2,804,823 9/ 1957 Iablansky 102-49.4 2,834,293 5/1958l Beach et al. 102--35.6 X

SAMUEL W. ENGLE, Primary Examiner U.S. Cl. X.R. N12- 4, 34.4 

